The present invention relates to the field of devices for indicating the proper heating of food.
Food originating form animal sources may often contain certain infectious microorganisms. Some of these microorganisms are resistant to temperatures which are less than the boiling temperature of water, but will perish if the food is cooked at a higher temperature. For example, an organism that is responsible for about 75% of the cases of food poisoning in the USA, Escherichia Coli, will be killed at about 75 degrees centigrade. A virulent variant, Coli 0-157 was responsible for mass infection of over 8000 people in the city of Sakai, Japan. The source of the infection was identified as partially cooked beef liver. The food in this case was cooked in a central kitchen and distributed to a number of municipal schools. Apparently, the dining room supervisor had not been aware of the fact that the food was improperly cooked, and that the required cooking temperature was not reached.
Had the food been cooked at a temperature that kills the bacteria, such massive food poisoning could have been avoided.
Therefore, among the objects of the present invention is to provide a device for determining whether a food substance was cooked to a required temperature. The device operates by exhibiting a detectable change after reaching the required cooking temperature.
It is a feature of the device that the detectable change is stable when the food is cooled after cooking.
Another feature of the device is that it is made of such materials and structure that permit direct contact with the food.
Yet another feature of the device is that it contains substances of such nature and in such quantities that even if the device is inadvertently swallowed by a person or ruptured during cooking dispersing its contents into the cooked food, it will not cause any significant harm to a person swallowing the device or s ingesting the food which the contents of the ruptured device were dispersed.
Still another feature of the device of the present invention is that the detectable change will be caused by the temperature change, and that no other action, such as mechanical action, is required.
There is therefore provided, in accordance with a preferred embodiment of the present invention, a device for indicating reaching of a temperature within a predetermined temperature range by a heated substance. The device includes a transparent sealed container including a first compartment having a first substance therein. The second substance therein, and a meltable sealant separating the first compartment from the second compartment. The meltable sealant has a melting point at a temperature within the predetermined temperature range. On reaching a temperature within the predetermined temperature range the meltable sealant melts enabling the first substance to contact the second substance. The contact between the first substance and the second substance results in a detectable change in at least one of the first substance and the second substance.
Further, in accordance with another preferred embodiment of the present invention, the second compartment is a second container placed within the transparent sealed container.
Further, in accordance with yet another preferred embodiment of the present invention, the heated substance is food and the first substance and second substance are non-toxic in the quantities used within the device.
Further, in accordance with another preferred embodiment of the present invention, the detectable change is a visible color change.
Furthermore, in accordance with another preferred embodiment of the present invention, the detectable change is stable upon cooling the device.
Furthermore, in accordance with another preferred embodiment of the present invention, the meltable sealant is a wax.
Furthermore, in accordance with another preferred embodiment of the present invention, the device is disposable.
Furthermore, in accordance with another preferred embodiment of the present invention. The device also includes an elongated member attached to the transparent sealed container for placing the transparent container within the heated substance and for retrieving the transparent container from within the heated substance.
Further, in accordance with another preferred embodiment of the present invention, the transparent sealed container is an elongated container having a first end and a second end. The first end is inserted into a portion of the heated substance such that the second end protrudes out of the portion for enabling the detectable change occurring when the inner part of the portion reaches the temperature to be detected at the second end.
Furthermore, in accordance with another preferred embodiment of the present invention, at least one of the first end and second end is tapered to facilitate inserting the transparent sealed container into the portion.
Furthermore, in accordance with another preferred embodiment of the present invention, the portion of the heated substance is a piece of meat to be cooked and the device is used to determine whether the inner portion of the piece of meat has reached the temperature.
Furthermore, in accordance with another preferred embodiment of the present invention, the first substance is a solution of a pH sensitive indicator dye or a pH sensitive dye in a solid form and the second substance is a solid or solution capable of changing the pH of the first substance upon mixing therewith to a value sufficient to cause a detectable color change in the first substance. At least one of the first substance and second substance is a liquid.
Furthermore, in accordance with another preferred embodiment of the present invention, the first substance is a solution of a leuco dye in aqueous ethanol, and the second substance is selected from the group consisting of a solution of citric acid in ethanol, an aqueous solution of citric acid and crystals of citric acid.
Furthermore, in accordance with another preferred embodiment of the present invention, the first substance is a solution of the leuco dye Copikem 7 in 95% ethanol 5% water, and the second substance is selected from the group consisting of a solution of 0.5% citric acid in 95% ethanol 5% water, an aqueous solution of citric acid and crystals of citric acid.
There is also provided a method for determining whether a heated substance has reached a temperature within a predetermined temperature range. The method uses a device including a transparent sealed container. The transparent sealed container includes a first compartment having a first substance therein, a second compartment having a second substance therein and a meltable sealant separating the first compartment from the second compartment. The meltable sealant has a melting point at a temperature within the predetermined temperature range. On reaching a temperature within the predetermined temperature, the meltable sealant melts enabling the first substance to contact the second substance. The contact between the first substance and the second substance results in a detectable change in at least one of the first substance and second substance. The method includes the steps of inserting at least part of the device into the heated substance and checking at least part of the transparent sealed container subsequent to the step of inserting to determine whether the detectable change occurred within the transparent sealed container.